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UNS N07718 – Chemical composition

May 7, 2017 by Mariano Iannuzzi

Spreadsheet version

An always up-to-date spreadsheet with composition, heat treatments, and mechanical properties can be obatined HERE.

API 6ACRA Chemical Composition

This is UNS N07718 chemical composition as per the American Petroleum Institute (API) 6ACRA standard.[1]ref1

Element Wt%
Ni 50.0 –55.0
Cr 17.0 – 21.0
Mo 2.80 – 3.30
W —
Fe balance
Nb —
Nb + Ta 4.87 – 5.20
Ti 0.80 – 1.15
Al 0.40 – 0.60
C 0.045 max.
Mn 0.35 max.
Co 1.00 max.
Cu 0.23 max.
Si 0.35 max.
P 0.010 max.
S 0.010 max.
B 0.060 max.
Pb 0.0010 max.
Ca 0.0030 max.
Mg 0.0060 max.
PREN (PREN, W) 26.24–31.89 (26.24–31.89)

Where:

$$ {\text{PRE}_{\text{N}}} = {{\text{wt%Cr}}} + 3.3 \cdot {\text{wt%Mo}} + 16 {\text{wt%N}} $$

$$ {\text{PRE}_{\text{N, W}}} = {{\text{wt%Cr}}} + 3.3 \cdot \left( {{{\text{wt%Mo}}} + 0.5 {\text{wt%W}}} \right) + 16 {\text{wt%N}} $$

More information

Heat treatment requirements and mechanical properties can be consulted here.

Reference

  1. ref1

    API 6ACRA, “Age-hardened Nickel-based Alloys for Oil and Gas Drilling and Production Equipment” (Houston, TX: American Petroleum Institute, 2015).↩

Filed Under: Nickel Alloys, Tables Tagged With: api 6acra, chemical composition, na718, nickel alloys, tables, uns n07718

Professor | Director Curtin Corrosion Centre
Chevron & Woodside Chair in Corrosion | Curtin University
Adjunct Professor
Norwegian University of Science and Technology (NTNU)

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